Compressor



Nov. 1, 1966 CQNRAD ET AL COMPRESSOR Filed Sept. 6, 1963 FIG. I

FIG. 2

INVENTORS.

N A M W D S b A R W W W m sm 9 AE UHH Y B /6 3 Q ATTORNEY-5:

United States Patent 3,282,260 COMPRESSOR Ulrich Conrad,Ludwigsburg-Ossweil, Hans Dinger, Stuttgart, and Herbert Deutschmann,Stuttgart-Bad Cannstatt, Germany, assignors to Daimler-BenzAktiengesellschaft, Stuttgart, Unterturkheim, Germany Filed Sept. 6,1963, Ser. No. 307,237 Claims priority, application Germany, Sept. 15,1962,

14 Claims. (c1. 123-55 The present invention relates to a chargingblower or supercharger for internal combustion engines, especially thosedriven from an exhaust gas turbine, having an axial air inlet into therotor and a radial air discharge out of the rotor and provided with aring-shaped diifusor arranged about the rotor either with or withoutradially extending guide members.

With the known prior art charging blowers or superchargers of theaforementioned type, the delivery of the compressed air out of theblower takes place through spiral guide means. This results oftentimesin the disadvantageous necessity for a multiple deflection of the airand/or for the insertion of further diifusors. Additionally, this typeof construction is not suitable for internal combustion engines having acompact construction and a smooth external contour by reason of theoutwardly separate inlet and outlet lines.

The present invention aims at an improvement with respect to thesedisadvantages. The present invention solves the problems existing withthe aforementioned types of prior art blowers or superchargers in thatthe diflusor passes over with an annular gap into an axially adjoining,approximately cylindrical air pressure tank or header and in that theair inlet line extending axially from the charger inlet extends throughthis air pressure tank or header.

By the use of such an arrangement, a closed outer contour is achieved atthe blower so that it may be readily adapted to the engine block.Furthermore, the space requirement becomes smaller because the air inletand outlet lines are arranged one stacked within the other so to speakof. Additionally, by the use of the present invention, a better airguidance may be achieved without the use of further diffusors.

With internal combustion engines of in-line construction, the presentinvention proposes that the air pressure tank or header is disposedparallelly to the axis of the engine inlet manifold or inlet stack anddirectly passes over into the same without any air deflections. Hence,the blower axis is then disposed parallel to the axis of the inletmanifold or inlet stack or even is in alignment therewith. Such anarrangement produces an almost ideal air guidance and additionally avery good constructional installation particularly as according to afurther feature and development of the present inventive concept, theair pressure tank or header is formed itself by an extension andpossibly by an enlargement of the inlet stack or manifold whereby theblower with its housing may then be secured at a flange disposed alongthe end face thereof.

The present invention is also particularly suitable for use withinternal combustion engines of V-type construction. If used with suchtypes of engines, it is proposed that the air pressure tank or header beclosed at the end face thereof opposite the blower and be provided witha lateral aperture for the connection with the engine intake stack ormanifold. The blower axis is then approximately at right angle to theaxis of the inlet manifold or stack. This produces a good connection ofthe exhaust gas turbine with the exhaust manifold or stack of theinternal combustion engine.

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With such an arrangement, an intermediate member secured at the engineblock is inserted, according to the present invention, between theheader and the engine intake manifold or stack, which intermediatemember serves as bearer for the pressure air tank or header includingthe blower flangedly connected thereto. This bearer may be securedbetween the rows of cylinders at the engine block or engine frame andmay serve simultaneously for two blowers disposed in a mirror-image-likemanner relative to one another whereby one blower is provided for eachcylinder row. In that connection, it should be noted that, of course,the mirror-image-like arrangement of two blowers, for example, at bothends of the inlet stacks or manifolds is also possible with other typesof internal combustion engine constructions, as in general severalblowers constructed in accordance with the present invention may also beprovided with all types of internal combustion engines.

With the two aforementioned embodiments, the air inlet line isappropriately formed by a bent pipe section or elbow portion whichconnects the air inlet aperture at the blower with a lateral aperture ofthe air pressure tank or header. The lateral aperture is disposed withinternal combustion engines of V-type construction approximatelyopposite the aperture intended for the connection with the engine inletstack or manifold.

It is possible, of course, that the air pressure tank or header isformed directly by the blower housing itself. However, for reasons ofmanufacture and assembly, a division is normally preferred whereby theblower is then flangedly connected with the air pressure tank and theair pressure tank is again flangedly connected with the engine inletstack or manifold. In all cases, however, the air pressure tank mayserve, for example, with the aid of the aforementioned intermediatepiece as bearer element for the blower and exhaust gas turbine.Furthermore, it is also understood that the present invention is notlimited to a drive by means of an exhaust gas turbine but that any othersuitable known blower drive may be used, for example, by a counter shafttransmission.

Accordingly, it is an object of the present invention to provide acharging blower for internal combustion engines which eliminates bysimple means the drawbacks and disadvantages mentioned hereinabove andnormally encountered with the prior art constructions.

Another object of the present invention resides in the provision of acharging blower assembly for internal combustion engines which assuresas simple as possible a delivery of the air without unnecessarydeflections and deviations, permits a compact construction and minimizesthe need for several dilfusors.

A still further object of the present invention resides in the provisionof a charging blower assembly for internal combustion engines which maybe readily installed at the engine block in such a manner as not todisturb the relatively smooth and compact external contour of theinternal combustion engine blocks.

Another object of the present inventiton resides in the provision of acharging blower assembly, particularly such assembly as includes anexhaust gas turbine drive, which requires less space, can be readilysecured and assembled at the engine block and minimizes the number ofparts necessary therefor.

Still another object of the present invention resides in the provisionof a charging blower assembly for internal combustion engines which isnot only simple in structure but also permits an extremely uncomplicatedconnection with the inlet stack of the engine as well as with the outletstack in case of use ofexhaust gas turbines as drive means for theblowers.

These and other objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawing which shows, forpurposes of illustration only, two embodiments in accordance with thepresent invention and wherein:

FIGURE 1 is a partial cross-sectional view through a blower for aninline internal combustion engine, showing the engine in side view, and

FIGURE 2 is a partial cross-sectional view through a blower assembly inaccordance with the present invention for a V-type engine with theengine seen in plan view.

Referring now to the drawing wherein like reference numerals are usedthroughout the two views to designate like parts and more particularlyto FIGURE 1, reference numeral designates therein the engine block whichis not shown in detail and may be of any conventional construction. Aninlet manifold or inlet stack II is arranged at the engine block 10.Individual supply lines or delivery lines 12 lead from the stack 11 tothe cylinders 13. The inlet manifold or stack 11 is somewhat enlarged atone end thereof and forms an approximately cylindrical air pressure tankor header 14. The axis 15 of this air pressure tank M, which is at thesame time the blower axis, is disposed parallel to the longitudinal axisof the inlet stack Ill. The blower generally designated by referencenumeral 17 is arranged at the end face of the air pressure tank 14 bymeans of a flanged connection 16. The blower 17 is constructed as radialblower with a central air inlet 18 into the rotor 19 and an annularlyshaped diffuser 20 disposed about the rotor 19 which diffuser 20 may beconstructed either with or without approximately radially extendingguide elements.

A bent pipe or elbow section 22 leads from a lateral aperture 23 of theair pressure tank 14 to the central air inlet nipple 18 of the blower17. The elbow section 22 is inserted into the lateral aperture 23 insealing relationship by means of a flange 24. In the illustrated blower,the compressed air leaves the diffuser 20 through an annular gap 25through which it enters into the air pressure tank or header 14 and isconducted on from the air pressure tank 14 without any furtherdeflection into the inlet stack 11. Consequently, pressure losses causedby any possible deflections or deviations are avoided by the presentinvention. In the instant case, an exhaust gas turbine generallydesignated by reference numeral 26 serves for purposes of driving theblower 17 which exhaust gas turbine is operatively connected in anyknown manner with the exhaust manifold or exhaust stack of the engine.

It is, of course, understood that with the arrangement described so far,the housing of the blower 17 may also itself form the air pressure tank14. In that case, the flanged connection 16 is displaced into the plane27. However, it is also within the scope of the present invention tomake the elbow section 22 in one piece with the air pressure tank I4.Since, however, the inner sides of the channels serving for the airguidance should be as clean and smooth as possible, it is preferred forpurposes of improved and facilitated blasting and cleaning to utilizethe illustrated construction.

According to FIGURE 2, one blower each generally designated by referencenumeral 30 having an exhaust gas turbine generally designated byreference numeral 31 is coordinated to a respective cylinder row 28 ofthe internal combustion engine 29 of V-type construction. Also in thisembodiment an air pressure tank or header 21 adjoins the diffusor of theblower 30, in principle, in the same manner as already described. Theair pressure tank 21, however, is in this case closed at the end side 32thereof opposite the blower 30 and is provided with a lateral aperture33 for the connection with the engine inlet manifold or stack 34. Thisconnection, however, does not take place directly but instead by theinterposition of an intermediate piece 35 which is common to the blowers30 on both sides. The intermediate piece 35 is secured centrally at theengine block and serves simultaneously as bearer for the air pressuretanks or headers 21 inclusive of the charging blower assemblies thereof.The construction of the bent or elbow section 22 for the air inlet isthe same as described in connection with FIG- URE 1. The arrangement isthereby so made that the air inlet aperture 23 is disposed approximatelyopposite the aperture 33 for the connection With the inlet stack 34. Asmay be readily recognized from the drawing, the exhaust gas turbine 31may then be connected in a very favorable manner by a single bent orelbow section 36 with the exhaust manifold or stack 28 of the internalcombustion engine.

While we have shown and described two embodiments in accordance with thepresent invention, it is understood that the same is not limited theretobut is susceptible of numerous changes and modifications within thespirit and scope thereof as known to a person skilled in the art; andwe, therefore, do not wish to be limited to the details shown anddescribed herein but intend to cover all such changes and modificationsas are encompassed by the scope of the appended claims.

We claim:

I. A blower assembly for internal combustion engines, comprising:

blower means including rotor means and provided with a substantiallyaxial air inlet means into said rotor means and with substantiallyradial air outlet means out of said rotor means, and substantiallyannularly shaped diffusor means arranged about said rotor means,

air pressure tank means provided with a lateral aperture for the airinlet means,

means forming an annular gap disposed radially adjacent said annularlyshaped diffuser means, said annular gap means constituting a connectingpassage joining'said diifusor means and said air pressure tank means,

and air inlet line means extending from said air inlet means throughsaid air pressure tank means,

said air inlet line means including a bent conduit section whichconnects the air inlet line means at the blower means with the lateralaperture provided in the air pressure tank means for the air inlet.

2. A blower assembly for internal combustion engines according to claimI, wherein,

said air pressure tank means is of approximately axially symmetricalconstruction,

said engine being provided with engine intake means,

and the axis of said air pressure tank means being disposedsubstantially parallel to the axis of the engine intake means andpassing over substantially directly without deflections into said engineintake means.

3. A blower assembly for internal combustion engines according to claimI, wherein,

said air pressure tank means is of approximately axially symmetricalconstruction,

said engine being provided with engine intake means,

and the axis of said air pressure tank means being disposedsubstantially parallel to the axis of the engine intake means andpassing over substantially directly without deflections into said engineintake means,

said air pressure tank means being formed by an extension andenlargement of said engine intake means, and said blower means having ablower housing secured at a flange means provided at the end face ofsaid extension forming said air pressure tank means.

4. A blower assembly for internal combustion engines of V-typeconstruction having engine intake means, comprising:

blower means including rotor means and provided with a substantiallyaxial air inlet means into said rotor means and with substantiallyradial air outlet means out of said rotor means, and substantiallyannularly shaped diffusor means arranged about said rotor means,

air pressure tank means,

means forming an annular gap disposed radially adjacent said annularlyshaped ditfusor means, said annular 'gap means constituting a connectingpassage -vjoining said ditfusor means and said air pressure tank means,

and air inlet line means extending from said air inlet means throughsaid air pressure tank means,

said engine being provided with engine intake means,

said air pressure tank means being closed on the side thereof oppositesaid blower means and being provided with lateral aperture means for theconnection with the air inlet line means,

,said air inlet line means including a bent conduit section connectingsaid air inlet means at the blower means with said lateral aperturemeans.

5. A blower assembly for internal combustion engines according to claim1, wherein,

said air pressure tank means is of approximately axially symmetricalconstruction,

said engine being provided with engine intake means,

and the axis of said air pressure tank means being disposedsubstantially parallel to the axis of the engine intake means andpassing over substantially directly without deflections into said engineintake means,

said air pressure tank means being formed by an extension andenlargement of said engine intake means, and said blower means having ablower housing secured at a flange means provided at the end face ofsaid extension forming said'air pressure tank means,

said air pressure tank means being formed by the blower housing itself.

6. A blower assembly for internal combustion engines of V-typeconstruction having engine intake means, comprising:

blower means including a blower housing, rotor means and provided with asubstantially axial air inlet means into said rotor means and withsubstantially radial air outlet means out of said rotor means, andsubstantially annularly shaped dilrusor means arranged about said rotormeans, 2

air pressure tank means,

means forming an annular gap disposed radially adjacent said annularlyshaped ditfusor means, said annular gap means constituting a connectingpassage joining said ditfusor means and said air pressure tank means,

and air inlet line means extending from said air inlet means throughsaid air pressure tank means,

said engine being provided with engine intake means,

said air pressure tank means being closed on the side thereof oppositesaid blower means and being provided with lateral aperture means for theconnection with the air inlet line means,

said air pressure tank means being formed by the blower housing itself,

said air inlet line means including a bent conduit section connectingsaid air inlet line means at the blower means with said lateral aperturemeans.

7. A blower assembly for internal combustion engines having engineintake means, comprising:

blower means including rotor means and provided with a substantiallyaxial air inlet means into said rotor means and with substantiallyradial air outlet means out of said rotor means, and substantiallyannularly shaped diffusor means arranged about said rotor means,

air pressure tank means provided with a lateral aperture for the airinlet means,

means forming an annular gap disposed radially adjacent said annularlyshaped diffusor means, said annular gap means constituting a connectingpassage joining said diffusor means and said air pressure tank means,

and air inlet line means extending from said air inlet means throughsaid air pressure tank header means,

said'air pressure tank means being provided with a further lateralaperture for the connection with said engine intake means,

said air pressure tank means being formed by the blower housing itself,

and the further aperture provided in said air pressure tank means forthe connection with the engine intake means and the air inlet aperturereceiving the air inlet means being disposed approximately opposite oneanother.

8. A blower assembly for internal combustion engines of V-typeconstruction having engine intake means, comprising:

blower means including rotor means and provided with a substantiallyaxial air inlet means into said rotor means and with substantiallyradial air outlet means out of said rotor means, and substantiallyannularly shaped diifusor means arranged about said rotor means,

air pressure tank means,

said air pressure tank means being provided with a lateral aperture forthe air inlet means,

means forming an annular gap disposed radially adjacent said annularlyshaped ditfusor means, said annular gap means constituting a connectingpassage joining said diffusor means and said air pressure tank means, I

and air inlet line means extending from said air inlet means throughsaid air pressure tank means,

said engine being provided with engine intake means,

said air pressure tank means being closed on the side thereof oppositesaid blower means and being provided with lateral aperture means for theconnection with the engine intake means,

said air inlet line means including a bent conduit section whichconnects the air inlet means at the blower means with the lateralaperture provided in the air pressure tank means for the air inlet.

9. A blower assembly for internal combustion engines of V-typeconstruction having engine intake means, comprising:

blower means including rotor means and provided with a substantiallyaxial air inlet means into said rotor means and with substantiallyradial air outlet means out of said rotor means, and substantiallyannularly shaped ditfusor means arranged about said rotor means,

air pressure tank means,

said air pressure tank means being provided with a lateral aperture forthe air inlet means,

means forming an annular gap disclosed radially adjacent said annularlyshaped diflusor means, said annular gap means constituting a connectingpassage joining said diffusor means and said air pressure tank means,

and air inlet line means extending from said air inlet means throughsaid air pressure tank means,

said engine being provided with engine intake means,

said air pressure tank means being closed on the side thereof oppositesaid blower means and being provided with lateral aperture means for theconnection with the engine intake means,

said air inlet line means including a bent conduit section whichconnects the air inlet means at the blower means with the lateralaperture provided in the air pressure tank means for the air inlet,

and the further aperture provided in said air pressure tank meansintended for the connection with the engine inlet means and the airinlet aperture receiving the bent conduit section being disposedapproximately opposite one another.

10. A blower assembly for internal combustion engines of V-typeconstruction having engine intake means comprising:

blower means including rotor means and provided with a substantiallyaxial air inlet means into said rotor means and with substantiallyradial air outlet means out of said rotor means, and substantiallyannularlyshaped diffusor means arranged about said rotor means,

air pressure tank means,

said air pressure tank means being provided with a lateral aperture forthe air inlet means,

means forming an annular gap disposed radially adjacent said annularlyshaped difiusor means, said annular gap means constituting a connectingpassage joining said difiusor means and said air pressure tank means,

and air inlet line means extending from said air inlet means throughsaid air pressure tank means,

said engine being provided with engine intake means,

said air pressure tank means being closed on the side thereof oppositesaid blower means and being provided with lateral aperture means adaptedfor connection with the engine intake means,

said air inlet means including a bent conduit section which connects theair inlet means at the blower means with the lateral aperture providedin the air pressure tank means for the air inlet,

and said lateral aperture means and said air inlet aperture includingsaid bent conduit section being disposed approximately opposite oneanother,

and an intermediate structural part inserted between said air pressuretank means and the engine intake means which is secured at the engineblock and serves as bearer means for the air pressure tank means.

11. A blower assembly for internal combustion engines of V-typeconstruction having engine intake means, comprising:

blower means including rotor means and provided with a substantiallyaxial air inlet means into said rotor means and with substantialy radialair outlet means out of said rotor means, and substantiallyannularlyshaped diifusor means arranged about said rotor means,

air pressure tank means,

said air pressure tank means being provided with a lateral aperture forthe air inlet means,

means forming an annular gap disposed radially adjacent said annularlyshaped difiusor means, said annular gap means constituting a connectingpassage joining said diifusor means and said air pressure tank means,

and air inlet line means extending from said air inlet means throughsaid air pressure tank means,

said engine being provided with engine intake means,

said air pressure tank means being closed on the side thereof oppositesaid blower means and being provided with lateral aperture means for theconnection with the engine intake means,

said air inlet line means including a bent conduit section whichconnects the air inlet means at the blower means with the lateralaperture provided in the air pressure tank means for the air inlet,

and said lateral aperture means and said air inlet aperture includingsaid bent conduit section being disposed approximately opposite oneanother,

and an intermediate structural part inserted between said air pressuretank means and the engine intake means which is secured at the engineblock and serves as bearer means for the air pressure tank meansinclusive the flangedly connected blower means,

two blower means of substantially mirror-image-like arrangement beingprovided, one for each cylinder row, and both of said blower means beingsupported on said common bearer means between the cylinder rows of theengine.

12. A blower assembly for internal combustion engines, especiallyprovided with drive means in the form of an exhaust gas turbine,comprising:

blower means including rotor means and provided with a substantiallyaxial air inlet means into said rotor means and with substantiallyradial air outlet means out of said rotor means, and substantiallyannularlyshaped ditlusor means arranged about said rotor means andprovided with radially extending guide means,

air pressure tank means of approximately cylindrical construction,

means forming an annular gap disclosed radially adjacent said annularlyshaped dilfusor means, said annular gap means constituting a connectingpassage joining said diflusor means and said air pres sure tank means,

and air inlet line means in the form of an elbow section extending fromsaid axial air inlet means through said air pressure tank means, saidair pressure tank means being provided with a lateral aperture for saidair inlet line means.

13. A blower assembly for internal combustion engines having engineintake means especially provided with drive means in the form of anexhaust gas turbine, comprising:

blower means including a blower housing, rotor means and provided with asubstantially axial air inlet means into said rotor means and withsubstantially radial air outlet means out of said rotor means, andsubstantially annularly-shaped diffusor means arranged about said rotormeans and provided with radially extending guide means,

air pressure tank means provided with a lateral aperture for the airinlet means of approximately cylin drical construction,

means forming an annular gap disposed radially adjacent said annularlyshaped ditfusor means, said annular gap means constituting a connectingpassage joining said diffusor means and said air pressure tank means,

and air inlet line means in the form of an elbow section extendingaxially from said air inlet means through said air pressure tank headermeans,

said air pressure tank means being provided with a further lateralaperture for the connection with said engine intake means,

said air pressure tank means being formed by the blower housing itself,

said air inlet line means including a bent conduit section whichconnects the air inlet means at the blower means with the lateralaperture provided in the air pressure tank means for the air inlet,

and the further aperture provided in said air pressure tank means forthe connection with the engine intake means and the air inlet aperturereceiving the elbow section of said air inlet means being disposedapproximately opposite one another.

14. A blower assembly for internal combustion engines, according toclaim 1, wherein,

said air pressure tank means is of approximately axially symmetricalconstruction,

said engine being provided with engine intake means,

and the axis of said air pressure tank means being disposedsubstantially parallel to the axis of the engine intake means andpassing over substantially directly without deflections into said engineintake means,

9 10 said air pressure tank means being formed by an ex- ReferencesCited by the Examiner tension and enlargement of said engine intakemeans, UNITED STATES PATENTS and said blower means having a blowerhousing secured at a flange means provided at the end face 2,695,13111/1954 Prlce 230*127 of said extension forming said air pressure tank 511011890 8/1963 Carlson XR 3 1 5 H1; 1 d b t d t FOREIGN PATENTS an saiair me me means mcu mg a en con n1 section Which connects the air inletmeans at the 26849 10/1954 Fmland blower means with a lateral apertureprovided in the air pressure tank header means for the air inlet 10 MARKNEWMAN Prlmary Examine" line means. W. E. BURNS, Assistant Examiner.

11. A BLOWER ASSEMBLY FOR INTERNAL COMBUSTION ENGINES OF V-TYPECONSTRUCTION HAVING ENGINE INTAKE MEANS, COMPRISING: BLOWER MEANSINCLUDING ROTOR MEANS AND PROVIDED WITH A SUBSTANTIALLY AXIAL AIR INLETMEANS INTO SAID ROTOR MEANS AND WITH SUBSTANTIALLY RADIAL AIR OUTLETMEANS OUT OF SAID ROTOR MEANS, AND SUBSTANTIALLY ANNULARLYSHAPEDDIFFUSOR MEANS ARRANGED ABOUT SAID ROTOR MEANS, AIR PRESSURE TANK MEANS,SAID AIR PRESSURE TANK MEANS BEING PROVIDED WITH A LATERAL APERTURE FORTHE AIR INLET MEANS, MEANS FORMING AN ANNULAR GAP DISPOSED RADIALLYADJACENT SAID ANNULARLY SHAPED DIFFUSOR MEANS, SAID ANNULAR GAP MEANSCONSTITUTING A CONNECTING PASSAGE JOINING SAID DIFFUSOR MEANS AND SAIDAIR PRESSURE TANK MEANS, AND AIR INLET LINE MEANS EXTENDING FROM SAIDAIR INLET MEANS THROUGH SAID AIR PRESSURE TANK MEANS, SAID ENGINE BEINGPROVIDED WITH ENGINE INTAKE MEANS, SAID AIR PRESSURE TANK MEANS BEINGCLOSED ON THE SIDE THEREOF OPPOSITE SAID BLOWER MEANS AND BEING PROVIDEDWITH LATERAL APERTURE MEANS FOR THE CONNECTION WITH THE ENGINE INTAKEMEANS, SAID AIR INLET LINE MEANS INCLUDING A BENT CONDUIT SECTION WHICHCONNECTS THE AIR INLET MEANS AT THE BLOWER MEANS WITH THE LATERALAPERTURE PROVIDED IN THE AIR PRESSURE TANK MEANS FOR THE AIR INLET, ANDSAID LATERAL APERTURE MEANS AND SAID AIR INLET APERTURE INCLUDING SAIDBENT CONDUIT SECTION BEING DISPOSED APPROXIMATELY OPPOSITE ONE ANOTHER,AND AN INTERMEDIATE STRUCTURAL PART INSERTED BETWEEN SAID AIR PRESSURETANK MEANS AND THE ENGINE INTAKE MEANS WHICH IS SECURED AT THE ENGINEBLOCK AND SERVES AS BEARER MEANS FOR THE AIR PRESSURE TANK MEANSINCLUSIVE THE FLANGEDLY CONNECTED BLOWER MEANS, TWO BLOWER MEANS OFSUBSTANTIALLY MIRROR-IMAGE-LIKE ARRANGEMENT BEING PROVIDED, ONE FOR EACHCYLINDER ROW, AND BOTH OF SAID BLOWER MEANS BEING SUPPORTED ON SAIDCOMMON BEARER MEANS BETWEEN THE CYLINDER ROWS OF THE ENGINE.